Advanced · Module 9 · Lesson 1 of 13

CPU Cache Hierarchy: L1/L2/L3 Topologies, Cache Lines, and Data Locality

Navigate the hardware memory wall, optimize L1/L2/L3 cache line utilization, leverage hardware prefetchers, and eliminate set-associativity conflict misses via loop tiling.

ProAbout 16 minutes

By the end you can

Differentiate L1, L2, L3 cache topologies, access latencies, and cache line transfers
Exploit spatial and temporal locality to maximize CPU memory bandwidth
Deconstruct physical memory addresses into Tag, Set Index, and Offset bitfields
Eliminate cache thrashing and capacity misses using cache-conscious loop tiling

Builds on Project: High-Throughput HTTP/1.1 Web Server.

01 · A question first

Why does iterating through a 4096 x 4096 matrix row-by-row take 15 milliseconds, while iterating column-by-column through the exact same elements takes over 300 milliseconds—a 20x performance penalty for doing identical mathematical work?

Make a guess before you read on.

02 · The idea

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What's inside

Start with the problem
How the idea works
Why it is correct: Set Associativity and Conflict Misses
Production Optimization: Cache Blocking (Loop Tiling)
What it costs
Pitfalls and variations
Where it is used